High optical power emitting, electrically pumped semiconductor devices, such as broad area lasers and optical amplifiers (herein collectively referred to as “broad area amplifiers”) are believed to be desired. However, filamentation is known to degrade output beam quality in broad area amplifiers. Filaments typically occur when broad area amplifiers are driven at high injection currents to provide high output powers.
Filaments form because high optical power density concentrated in a local area depletes the carrier inversion in that area, due to stimulated recombination. The local depletion of carrier inversion results in a localized increase in refractive index that lenses and focuses optical energy. Existing modal profile distortion, resulting from well-known effects at a stripe edge, a distorted input beam, facet reflections and/or material non-uniformities, for example, are also increased.
It is believed the problem of filamentation has led to a general failure to effectively realize diffraction-limited high optical power emitting broad area amplifiers. While lateral waveguide tapering has been proposed to somewhat reduce filamentation to higher optical powers, approaches to mitigate filamentation, and stabilize broad area amplifier operation, are believed to be desirable.